Antigen Express scientists have discovered that cells expressing MHC class II molecules in the absence of the MHC class II-associated Ii protein can act as effective cellular vaccines. Cells with the MHC class II+/Ii-phenotype simultaneously present endogenously synthesized antigens by both MHC class I and class II molecules to CD8+ and CD4+ T cells, respectively. When the Ii protein does not block the MHC class II molecules at synthesis, the epitope pool available for MHC class I is also available for presentation by MHC class II molecules, leading to the creation of very potent vaccine cells. In this SBIR, we will use our Ii-suppression technology to augment the efficacy of HIV DNA vaccines. We will: 1) clone the HIV gp120 gene into vectors containing our Ii-reverse gene construct. Dendritic cells that take up the vector will then both synthesize gp120 and form the MHC class II+/Ii-phenotype; 2) identify optimal routes of inoculation and delivery agents for the in vivo transfection of lymph node lymphocytes and dendritic cells and, 3) characterize the in vivo ability of Ii-RGC/gp120 containing vectors versus gp120 alone to generate gp120-specific T cell proliferation and gp120-specific CTL activity. Our experiments will establish the potential utility of developing Ii-RGC/gp120 DNA vectors as HIV vaccines in the clinic. In a Phase II program Ii-RGC/gp120 DNA vaccines will be tested in non-human primates for the induction of a protective immune response against pathogenic HIV infection. [unreadable] [unreadable] [unreadable]